Rapid manufacturer Proto Labs (NYSE:PRLB) reported record second-quarter 2014 earnings this morning, which were more or less in line with expectations. For the quarter, Proto Labs grew revenues by 33% year over year to $52.9 million, translating into $0.42 a share in earnings. Analysts were expecting that Proto Labs would grow its revenues by 29.4% to $51.4 million and take home $0.42 a share in earnings. Digging deeper, Proto Labs continues to execute well across its business and investors should be pleased that the long-term thesis remains on track.

Strong revenue growth continues
In April, Proto Labs acquired Fineline Prototyping, a 3-D printing as a service provider, in a move to bolster its rapid prototyping services for the product development market. Adjusting for Fineline's $2.1 million in revenue it contributed during the quarter, Proto Labs' core injecting molding and CNC machining services revenue grew by a healthy 27.6% year over year. This level of core revenue growth reinforces the notion that Proto Labs is continuing to deliver on its massive potential -- and could potentially be gaining market share on the competition.

Prlb Total Revenues

Source: Proto Labs.

A record number of product developers served
Tracking the number of unique product developers that Proto Labs serves can provide insight into whether or not Proto Labs' rapid manufacturing services are becoming more popular in the product development world. In the second quarter, Proto Labs served a record 8,222 unique product developers, which doesn't account for product developers served from its Fineline 3-D printing services. In other words, Proto Labs' rapid manufacturing services are clearly becoming more essential to product developers worldwide -- an encouraging sign for the company's long-term prospects.

Prlb Product Developers Served

Source: Proto Labs.

Revenue per product developer on the rise
The amount of revenue that Proto Labs generates on a per product developer basis can tell investors if customer spending and loyalty is on the rise. Over the long term, customer loyalty could become an important asset for Proto Labs should the competition begin to encroach on its turf. During the quarter, customer spending increased 7%, indicating that customer satisfaction remains strong, which creates the building blocks for enduring brand loyalty.

Prlb Revenue Per Product Developer

Source: Proto Labs, author's calculations.

Margins edged lower
Profit margins across the board edged slightly lower sequentially, which was likely negatively affected from the Fineline acquisition. Because 70% of Proto Labs' customers already take advantage of 3-D printing during the product development process, investors should view any profit margin declines related to Fineline as a way for Proto Labs to own more of the product development cycle. Assuming Proto Labs can maintain its pricing power and grow its overall market share with Fineline, the company should be able to make up for any profit margin declines with increased volume.

Prlb Profit Margins

Source: Proto Labs, author's calculations.

International growth should normalize
Proto Labs' international revenue sequentially dropped to 24.4% of its total revenue, meaning there's still plenty of untapped potential for the company overseas. In the coming quarters, Proto Labs plans to continue integrating its Fineline acquisition across its worldwide ecosystem, which should help normalize international revenues to a higher level.

Prlb International Revenues

Source: Proto Labs, author's calculations.

New services are coming
Proto Labs CEO Vicki Holt hinted that "several" new rapid manufacturing services would be introduced by its internal research and development team in the coming quarters. Each new service that Proto Labs introduces gives the company an opportunity to expand its addressable market and serve its customer base better. Building out its ecosystem helps ensure that Proto Labs' business will continue growing for years to come.

At the end of the day, Proto Labs issued another solid earnings report, driven by strong revenue growth, customer growth, and increasing customer satisfaction. Long-term investors should continue holding onto shares, and prospective investors should certainly consider buying shares.

Steve Heller owns shares of Proto Labs. The Motley Fool recommends Proto Labs. The Motley Fool owns shares of Proto Labs. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.